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Ground Penetrating Radar (GPR) is an important non-destructive and affordable geophysical prospecting tool for subsurface investigations across many professional fields, including archaeology, forensics, environmental assessment, agriculture, infrastructure, geological stratigraphy, glaciology, mineral exploration, and more. In archaeology, 2D or 3D GPR aids in searching and finding unmarked graves and burials, delineating the edges of historic cemeteries, mapping the foundations of ancient structures, and searching for artifacts and tombs.

Cordillera Geo-Services provides geophysical and geological field investigations to develop an understanding of your projects’ near-surface settings.

Cemeteries’ subsurface can be mapped in 3D with ground penetrating radar (GPR). Old unmarked graves can exist on roadside verges next to historic graveyards. Such unknown graves can be encountered during the expansion of an existing road or the construction of a new one. A 3D GPR survey is a tremendous non-destructive remote sensing technique that can identify old unmarked burials. Graveyard and roadside verge mapping is done easily with 3D GPR.

Cordillera Geo-Services provides geophysical and geological field investigations to develop an understanding of your projects’ near-surface settings.

Mapping cemeteries with Ground Penetrating Radar (GPR) before road construction begins is invaluable because it prevents unexpected findings such as unmarked graves or old utility lines. GPR is an important cost-effective, quick, non-destructive geophysical prospecting tool for subsurface investigations in many professional applications, including archaeology, environmental assessment, agriculture, infrastructure, geological stratigraphy, mineral exploration, and more. In archaeology, 2D or 3D GPR aids in the mapping of foundations of ancient structures, searching for artifacts and tombs, and finding graves and burials.

Cordillera Geo-Services provides geophysical and geological field investigations to develop a (1D/2D/3D) understanding of your projects’ near-surface settings.

Ground Penetrating Radar (GPR) is an important non-destructive, quick, affordable geophysical prospecting tool for subsurface investigations across many professional fields, including archaeology, forensics, environmental assessment, agriculture, and infrastructure, geological stratigraphy, glaciology, mineral exploration, and more. In archaeology, 2D or 3D GPR aids in searching and finding unmarked graves and burials, delineating the edges of historic cemeteries, mapping the foundations of ancient structures, and searching for artifacts and tombs. Cordillera Geo-Services provides geophysical and geological field investigations to develop an understanding of your projects’ near-surface settings.

This video shows how rebars within a concrete sidewalk (or slab) are mapped using 3D concrete scanning. In this case, the bi-directional imaging grid is 2 ft by 2 ft, but it can be smaller or larger. Various perpendicular profiles are collected side-by-side and generate a 3D image of the concrete slab. The 3D scan can be applied on horizontal, vertical, or inclined concrete surfaces over fresh, young, or mature concrete indoors or outdoors. 2D images can also be extracted from the resulting 3D image.

3D or 2D concrete scanning can reduce safety risks, financial exposure, and costly delays. This fast 3D imaging technique is ideal for concrete inspection and evaluation. It can efficiently and accurately locate the position and depth of metallic and non-metallic objects in concrete structures, including rebar, post-tension cables, voids, conduit, pan decking, and service utilities. Other typical uses include measuring slab thickness, pavement condition assessment, structure inspection, and locating archaeological artifacts buried in the soil.

Cordillera Geo-Services can assist if your geotechnical projects require shallow or deep subsurface imaging services.

Dr. Hinojosa provides a full field demonstration on how to set up and do a 2D seismic refraction tomography and gives a real example

This video is about the importance of scanning the underground at a site before, during, or after construction. Underground scanning is doable in 2D, 3D, and 4D (for some techniques) with the use of near-surface geophysical methods.

This video describes the basic principles of the 3D electrical resistivity imaging (ERI) applied in the real estate sector and provides a real example.

2D electrical resistivity imaging (ERI) is a widely used and accepted geophysical technique used to explore groundwater potential. ERI can decrease the uncertainty in the drilling phase. ERI can detect fractured zones affecting an aquifer, which facilitate well productivity. This video shows such an example.

Cordillera Geo-Services provides geophysical and geological field investigations to develop an understanding of your projects’ near-surface settings.

Often, historic mine sites are found in ruins. The small infrastructure that once supported the operations is often the physical evidence of historic mining operations. Quite frequently, the mine shafts are lost due to the growth of vegetation, or are backfilled and never used again. Electrical resistivity imaging (ERI) can help find the evidence of historic mine shafts and mine galleries and help identify unexploited or undiscovered ore. Cordillera Geo-Services provides geophysical and geological field investigations ad hoc to your projects’ needs.

This video shows the 2D electrical resistivity imaging (2D ERI) fieldwork done at the Gault Archaeological Site. 2D ERI was used to search for paleochannel deposits located between an active stream and an important archaeological excavation pit.

If your projects require subsurface imaging for a site investigation, we can assist you with that. Contact information: (737) 207-2536. Dr. Hector R. Hinojosa, P.G.

This video shows the use of 2D Electrical Resistivity Imaging (ERI) to investigate a water seepage at a public park (Austin, Texas, USA). In this case, water seepage has formed a pond in the park. ERI can explore the subsurface conditions across different sectors, including environmental, engineering, mining, land development, and archeology. Cordillera Geo-Services provides 2D, 3D, and 4D ERI services anywhere.

3D  Electrical Resistivity Imaging (ERI) applied in construction engineering projects Urbanization modifies our landscape and the ground conditions, and sometimes, the ground conditions are inadequate for urbanization. Urbanization in overpopulated karst regions is now becoming a common practice worldwide. Karst terrain is a natural landscape where either surface or groundwater slowly dissolves the underground or exposed soft rock like limestone, dolomite, marble, and gypsum, leaving karstic features prone to become geohazards. Critical karst features include caves, caverns, cavities, voids, sinkholes, and open fractures in urbanized and unurbanized areas. Urban karsts can hide unknown geohazards often discovered during construction or utility work. The unwanted discovery often leads to unexpected setbacks and extra costs. Non-invasive, near-surface investigations provide essential information for an urbanization project’s planning and development stages. 3D ERI can quickly identify unexpected shallow geohazards before, during, and after excavation or construction. This video shows an example.

The identification and mapping of caves, caverns, sinkholes, and voids are possible with shallow remote sensing geophysical methods. Karst terrain is a typical environment that produces such natural geohazards. Karst terrain is distinguished by the solubility in water of its bedrock, mainly limestone and dolomitic, or evaporitic rocks (like salt or gypsum), and is defined by its underground network of drainage and dissolution cavities. Karst terrain and topography create site-specific geohazards. Building in urban or remote karst terrains presents geotechnical challenges due to the variable and unpredictable ground conditions they present to construction engineers. It is vital to survey the surface and scan the subsurface so that caverns, caves, fissures, or sinkholes are not encountered during construction. The surface and subsurface studies are possible with geophysical and geological methods. 3D electrical resistivity imaging (ERI), a well-established geophysical method, can quickly identify such unexpected shallow geohazards, if present, before, during, and after excavation and construction.

This video exemplifies a non-metallic mineral (perlite) exploration project.

Perlite is a naturally occurring amorphous hydrated silicic volcanic glass of rhyolitic composition formed through secondary alteration by the slow diffusion of meteoric water into the glass/silica structure under low-temperature surficial conditions. Perlite is commonly vitreous in the field, with a pearly luster and concentric fractures, with colors ranging from transparent light gray to glossy black. Perlite’s geologic settings include the glassy parts of domes and lava flows of rhyolitic composition, pyroclastic and ignimbrites, vitric tephra, the chill margins of dykes and sills, and welded ash-flow tuffs. Crude perlite ore expands by a factor of 4 to 20 when rapidly heated to a suitable point (typically 760 to 1,200 °C) in an industrial expansion furnace. The industrial expansion process creates a product referred to as expanded perlite. Expanded perlite has various physical properties, including high porosity, low thermal conductivity, low bulk density, high sound absorption, high heat resistance, high surface area, and chemical inertness or stability. These properties make expanded perlite adaptable to commercial applications in several industries, including construction, chemical, air and liquid filtration, horticultural, and petrochemical.

Mexican perlite ore deposits are commonly hosted in rhyolitic lava flows and ignimbrite strata of the Late Oligocene–Early Miocene Sierra Madre Occidental (SMO) silicic large igneous province. From south to north, perlite ore deposits occur in Puebla, México, Jalisco, Michoacán, Sinaloa, Chihuahua, Durango, Sonora, and Baja California Norte. The Selene perlite ore deposit occurs along the tectonically extended western edge of the northern SMO in northeastern Sonora, Mexico. To document this deposit, we used traditional geological mapping within an area of 4 × 4 km combined with petrographic analysis of representative volcanic samples of rhyolitic and basaltic composition and local lithostratigraphic correlations with well-dated volcanic units of rhyolitic composition. The objective was to define the deposit’s occurrence and understand its volcanogenic context and formation process (Hinojosa et al., 2016 in Boletín de la Sociedad Geológica Mexicana).

Cordillera Geo-Services provides geological and geophysical services to develop an understanding of your projects’ near-surface settings.

Scanning the subsurface under an existing or future concrete slab is possible in 3D, using an electrical resistivity imaging (ERI) technique. A 3D ERI survey can assist in foundation issues in existing or future properties. 3D ERI is an underutilized geophysical exploratory technique despite being around for almost 20 years. Its engineering applications are numerous, and they mainly help “scanning the subsurface conditions.” A promising application of 3D ERI is in the Real Estate sector because of how the electrode cable is deployed. This video describes the basic principles of 3D ERI applied in the Real Estate sector and provides a real example.

Cordillera Geo-Services can provide geophysical and geological field investigations to develop a 3D understanding of your projects’ near-surface settings.

Mineshafts are structures exclusively indicative of underground mining activity. Often, historic mine sites are found in ruins or abandoned lands. The small infrastructure that once supported the operations is often the physical evidence of historic mining operations. The mineshafts are lost frequently due to vegetation growth or backfilled vegetation and never used again. Electrical resistivity imaging(ERI) can help find the evidence of historic mine shafts and mine galleries and help identify unexploited or undiscovered ore.

Cordillera Geo-Services provides geophysical and geological field investigations ad hoc to your projects’ needs.

The Gault Archaeological Site in central Texas, USA, is a spectacular place in the context of the hypothesis of peopling of the Americas over 13,000 years ago. The Gault site has yielded valuable information for the archaeological community. For instance, its oldest stratigraphic component is dated at more than 15,000 years. More than half a million artifacts of Clovis age (13,400-12,700 years ago) and intact Archaic deposits dating from nearly 5,000 to 9,000 years ago have been recovered. Paleoindian deposits from 13,000 to 10,000 years ago and incised stones among the oldest in the Americas exist.

This video shows the results of 2D electrical resistivity imaging (2D ERI) fieldwork at the Gault Archaeological Site. 2D ERI was used to search for paleochannel deposits between an active stream and an important archeological excavation pit.

Cordillera Geo-Services can assist you if your archaeological or environmental projects require subsurface imaging for a site investigation.

Remote sensing investigations are a synonym of geophysical surveying. There are numerous geophysical surveying methods — magnetometry is one of them. Magnetic surveying is a passive, non-intrusive, remote sensing technique widely used in different fields, including archeology, geological and mineral exploration, forensics investigations, environmental investigations, and engineering. The geophysical property of interest is known as “magnetic susceptibility.” A magnetometer measures the magnetic field intensity or signal in units of nanoTeslas (nT). There are three types of magnetometers: proton-precession, alkali-vapor, and fluxgate. Most magnetic surveys use proton-precession or fluxgate, which operate in stationary or moving mode. Fluxgate magnetometers measure the magnetic field in 3-directions and their magnitude. Proton-precession magnetometers and alkali-vapor magnetometers only measure the total magnetic field’s intensity. High-sensitivity alkali-vapor magnetometers in single-sensor or dual-sensor mode (gradiometer) are preferred for high-precision surveys.

Cordillera Geo-Services provides geophysical and geological services to develop an understanding of your projects’ near-surface settings.

The Transient Electromagnetic (TEM) exploration method is used to map for the presence of electrically conductive buried bodies. In the TEM method, a transmitting coil is energized with multiple current pulses separated by current-off periods. During the period of current-on, a static magnetic field is established in the subsurface earth materials. When the current in the transmitting coil (and thus the primary magnetic field) is rapidly switched-off, the EMF induced in the ground causes eddy currents to flow both in the ground and nearby conductive buried bodies. As a result of resistive heat loss, these currents decay with time, causing a decaying magnetic field at the ground surface. Since the secondary file is generated when the primary magnetic field is off, it can be measured relatively easily. Within highly conductive bodies, the decay of the eddy currents (and thus of the secondary magnetic fields) is significantly lower than in poor conductors. Thus, measurement of the secondary field rate provides a means of detecting subsurface conductive bodies and estimating their electrical conductivity.

Cordillera Geo-Services provides geophysical and geological services to develop an understanding of your projects’ near-surface settings.

Groundwater is a valuable natural resource. Most of our potable water often comes from groundwater wells. Finding groundwater is a process that uses geoscientific knowledge and technology. Some technology is either in the form of geophysical instruments for exploration or drilling rigs. Often, geophysical surveys reduce the risk of drilling a dried well. Doing a geophysical survey prior to drilling a water well is beneficial. There are various geophysical exploration methods. The Transient Electromagnetic (TEM) method is one of many.

This video provides an example of a geophysical survey for groundwater exploration in an ancient urbanized agricultural valley (Greece) using the TEM method. The TEM exploration method is used to map for the presence of electrically conductive buried bodies. In the TEM method, a transmitting coil is energized with multiple current pulses separated by current-off periods. During the period of current-on, a static magnetic field is established in the subsurface earth materials. When the current in the transmitting coil (and thus the primary magnetic field) is rapidly switched off, the emf induced in the ground causes eddy currents to flow both in the ground and nearby conductive buried bodies. As a result of resistive heat loss, these currents decay with time, causing a decaying magnetic field at the ground surface. Since the secondary file is generated when the primary magnetic field is off, it can be measured relatively easily. Within highly conductive bodies, the decay of the eddy currents (and thus of the secondary magnetic fields) is significantly lower than in poor conductors. Therefore, measurement of the secondary field rate detects subsurface conductive bodies and estimates their electrical conductivity.

Cordillera Geo-Services provides geophysical and geological services to develop an understanding of your projects’ near-surface settings.

This video is about the importance of scanning the underground at a construction site before (preferably), during, or after construction. Underground scanning is possible in 2D, 3D, and 4D (for some techniques) using near-surface geophysical methods.

Geological information plays a crucial role in addressing sustainable development challenges such as groundwater protection, land degradation and contributes to improved decision-making processes (Häggquist and Söderholm, 2015). Geological information is often useful for decision-making in a wide range of societal activities the sustain civilization, such as (1) discovering, understanding, and managing the causes of geologic hazards; (2) the exploration and development of minerals and fossil fuels; (3) the development, sustainable use, and protection of groundwater; (4) environmental impact assessments; (5) the construction of infrastructure projects; (6) city planning including zoning and landscaping; and (7) regional planning such as siting and permitting industrial facilities. An important example of a product containing geological information is the geological map. It describes the physical world by connecting spatially based information, geological materials (rocks, soils, water, to name a few), and geologic structures. Geological maps also add time and space interpretations on how these materials and structures interrelate. Detailed geological maps can reveal several benefits. It could influence mineral exploration and investment by reducing the risks at the early stages of the exploration process. In the engineering sector, shallow excavations are dependent on accurate knowledge concerning soil and bedrock conditions.

Perlite is a naturally occurring amorphous hydrated silicic volcanic glass of rhyolitic composition formed through secondary alteration by the slow diffusion of meteoric water into the glass/silica structure under low-temperature surficial conditions. Perlite is commonly vitreous in the field, with a pearly luster and concentric fractures, with colors ranging from transparent light gray to glossy black. Perlite’s geologic settings include the glassy parts of domes and lava flows of rhyolitic composition, pyroclastic flows and ignimbrites, vitric tephra, and the chill margins of dykes and sills, and welded ash-flow tuffs. Crude perlite ore expands by a factor of 4 to 20 when rapidly heated to a suitable point (typically 760 to 1,200 °C) in an industrial expansion furnace. The industrial expansion process creates a product referred to as expanded perlite. Expanded perlite has various physical properties, including high porosity, low thermal conductivity, low bulk density, high sound absorption, high heat resistance, high surface area, and chemical inertness or stability. These properties make expanded perlite adaptable to commercial applications in several industries, including construction, chemical, air and liquid filtration, horticultural, and petrochemical.

Mexican perlite ore deposits are commonly hosted in rhyolitic lava flows and ignimbrite strata of the Late Oligocene–Early Miocene Sierra Madre Occidental (SMO) silicic large igneous province. From south to north, perlite ore deposits occur in Puebla, México, Jalisco, Michoacán, Sinaloa, Chihuahua, Durango, Sonora, and Baja California Norte. The Selene perlite ore deposit occurs along the tectonically extended western edge of the northern SMO in northeastern Sonora, Mexico. To document this deposit, we used traditional geological mapping within an area of 4 × 4 km combined with petrographic analysis of representative volcanic samples of rhyolitic and basaltic composition and local lithostratigraphic correlations with well-dated volcanic units of rhyolitic composition. The objective was to define the deposit’s occurrence and understand its volcanogenic context and formation process (Hinojosa et al., 2016 in Boletín de la Sociedad Geológica Mexicana).

Cordillera Geo-Services provides geological and geophysical services to develop an understanding of your projects’ near-surface settings.

This short video explains how limestone might have voids in the subsurface and why it is super important to investigate and understand the subsurface for any construction project before construction begins. The video shows some small real caves in limestone located in an urban area (neighborhood), and explains how I help construction companies and land developers in the building process. Urbanization modifies the landscape and the ground conditions, but sometimes, the ground conditions are inappropriate for development. Urbanization can occur on many surface conditions, including soft or hard soils, loose sediments, or weathered or massive rock. The fact is that #landdevelopers, #cityplanners, and #constructionengineers ought to know the subsurface conditions before urbanization can even begin. Particularly, urbanization in overpopulated #karst terrains or regions is becoming common. Karst terrain is defined by its underground drainage and dissolution cavities and features. Karst terrain is a natural landscape where surface water or #groundwater slowly dissolves the exposed or underground rocks like #limestone, dolomite, marble, or gypsum, leaving #karstic features prone to become shallow site-specific #geohazards worldwide. These karstic features can include #caves, #caverns, #cavities, #voids, #sinkholes, and open #dissolution fractures, which might exist in urbanized, suburbanized, or unurbanized areas. #Urban #karsts can hide these unknown #geohazards that are often discovered during #construction or #utility work, leading to unpredicted delays and additional expenses. Building in karst terrains can be challenging due to the variable and unpredictable ground conditions they present to construction engineers. However, it is possible to detect unknown karstic features and evaluate geohazard risk before and during the infrastructure design or construction phases using geological and geophysical methods. Cordillera Geo-Services provides both geological and geophysical professional services.

This video is about the importance of interacting with karst terrain. Karst terrain distinguishes from other terrains by the solubility in water of its bedrock, mainly limestone (but can also be dolomite or evaporitic rocks like salt or gypsum), and is defined by its underground drainage and dissolution cavities and features. Natural ground fissures, caves, caverns, and sinkholes make up the main karst geohazards worldwide. Karst terrain and topography create site-specific geohazards. Building in karst terrains can be challenging due to the variable and unpredictable ground conditions they present to construction engineers. Building on karst terrain can discover caves, caverns, fissures, or sinkholes during construction. However, geophysical and geological methods can detect unknown caves, caverns, fissures, or sinkholes during the infrastructure design or construction phases.

Cordillera Geo-services provides both geological and geophysical services that can detect or map karstic features on the surface or subsurface.

Groundwater is a valuable natural resource, but we often do not know where and how deep it is. Most of our potable water usually comes from groundwater wells. The construction of a water well requires knowledge of where to drill, but first, you need to find locations with groundwater potential. Finding groundwater is a process that requires geoscientific expertise and technology such as geophysical instruments and a drilling rig. The actual construction of the water well is a different step and process. Performing a geophysical survey before drilling a water well is wise because it reduces the risk of drilling a dried well. Various geophysical exploration methods help find groundwater. The Seismoelectric method is one of them. This video provides a real example of a Seismoelectric survey for groundwater exploration in central Texas, USA. Cordillera Geo-Services provides geophysical and geological services that satisfy your projects’ needs.

Water is a finite and precious natural resource. We use geophysical exploration techniques to find the right spot(s) to drill successful wet water wells. The 3 ways to explore groundwater or subsurface water before drilling are ERI (Electrical Resistivity Imaging), TEM ( Transient Electromagnetic), and AMT (Audio-Magnetotelluric). Our services are provided where they are needed, even overseas.

Construction projects often demand Geotechnical information and services. Both geological and geophysical services often satisfy Geotechnical project needs. As a licensed Professional Geoscientist, I offer geological and geophysical services to engineering, energy, mining, water resources, environmental, and cultural resources management sectors.

Cordillera Geo-Services specializes in producing geological and geophysical data that concerns construction site conditions above and below the ground surface, which are valuable input for project design and development, the identification of geological hazards, and the exploration of natural resources – like water, minerals, and geothermal energy.

A person or firm that needs geological, geotechnical, and/or geophysical input for project design and development or to explore natural resources is considered the ideal client. So, if you are in the engineering, energy, mining, water resources, environmental, construction, and cultural resources management sector, I can help.